Hydraulic system



June 23, 1970 w. A. R'AY 3,516,332

HYDRAULIC SYSTEM 2 Sheets-Sheet 1 Filed June 17, 1968 V Q R My N 0 NS Q7 W. Q wwbm K33 mm A W x wk m W w June 23, 1970 Filed June 17, 1968 VAL(/5 W. A. RAY

HYDRAULIC SYSTEM 3 Sheets-Sheet 2 HVDEA UL /C PUMP INVENTOR. W A. 64 VUnited States Patent 3,516,332 HYDRAULIC SYSTEM William Alton Ray, NorthHollywood, Calif., assignor to International Telephone and TelegraphCorporation, New York, N.Y., a corporation of Delaware Filed June 17,1968, Ser. No. 737,773 Int. Cl. Fb 9/03, 9/09, 13/043 US. Cl. 91-48 3Claims ABSTRACT OF THE DISCLOSURE A solenoid valve-operated, restrictedorifice for a hydraulic system, including a hydraulic amplifier to causeslow de-actuation of the controlled device. The orifice at the output ofthe hydraulic amplifier may, thus, control an enormously larger force,and a very small solenoid valve may turn the system on and off.

BACKGROUND OF THE INVENTION SUMMARY OF THE INVENTION In accordance withthe device of the present invention, the above-described and otherdisadvantages of the prior art are overcome by providing a hydraulicsystem including a fluid pressure responsive device, motive power meansfor supplying a hydraulic fluid under pressure to the device, and ahydraulic amplifier having an input conduit from the motive power means,and an output conduit. In accordance with the invention, a fixedrestricted orifice is provided with a valve connected between the outputconduit of the amplifier and the orifice. The valve is movable to aposition for increasing the pressure of the fluid supplied from theamplifier to actuate the amplifier. The valve is also movable to an openposition to allow the pressure of the fluid in the output conduit todecrease slowly as the fluid escapes from the orifice. The fluidpressure responsive device may be a valve. In this case, the valve isclosed slowly.

The above-described and other advantages of the present invention willbe better understood from the following description when considered inconnection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings, which are to beregarded as merely illustrative:

FIG. 1 is a diagrammatic view of a hydraulic system constructed inaccordance with the present invention; and

FIG. 2 is a block diagram illustrating an alternative embodiment of theinvention:

DESCRIPTION OF THE PREFERRED EMBODIMENT In the drawing in FIG. 1, one'embodiment of the invention is indicated at 10, having a sum 11connected from sump 12 to an input conduit 13 of device 14 to becontrolled. Device 14 comprises a housing including an upper portion 15and a lower portion 16. Upper portion 15 has a control conduit 17connected thereto. Portion 16 has a vent port 18 therethrough. Device 14has a piston 19 therein sealed by an O-ring 20. Piston 19 has a rod 21fixed thereto slideable in a bore 22 in housing 3,516,332 Patented June23, 1970 ice portion 16. Control conduit 17 is connected to a hydraulicamplifier 23, having a ball valve 24. An arm 25 is pivoted at a pin 26to a bracket 27. Arm 25 assumes a position dependent upon the pressurein a chamber 28 inside amplifier 23. The ouiside of amplifier 23 is opento the atmosphere or reservoir pressure. A spring 29 urges a flexiblediaphragm 30 into chamber 28 by a backup plate 31. Diaphragm 30 andplate 31 are connected to arm 25 by a rod 32 pinned to arm 25 at 33. Theoutput conduit 34 of amplifier 23 is connected alternately to either oneof two bleed orifices 35 and 36 by a three-way solenoid valve 37.

The fluid output of orifice 36 is controlled by a system 38 that isidentical to that disclosed in US. Pat. No. 3,087,471. System 38includes a vane or flapper valve 50 which opens and closes orifice 36.Valve 50 is pivoted at 51 from fixed member 52. Valve 50 is fixed with aferromagnetic beam 53 which is attracted by electromagnets 54 and 55.One end of each electromagnets 54 and 55 is connected across a winding56 of a potentiometer 57 having a wiper 58 movable with rod 21. Theother ends of electromagnets 54 and 55 are connected across a winding 59of potentiometer 60 having a wiper 61 manually setable thereon. An ACsource of potential 62 is electrically connected between wipers 58 and61.

In the operation of the embodiment of the invention shown in FIG. 1,upward vertical movement of piston 19 is produced by a coiled spring 63,i.e., if the pressure above piston 19 is sufiiciently low.

The entire structure shown in FIG. 1 may be identical to that disclosed,for example, in FIG. 5 of the said patent, except that conduit 34 may bedirectly connected to orifice 36, and valve 37, a valve P, and orifice35 would be omitted. In the mode of operation herein, valve 37 providesfree and open communication between conduit 34 and orifice 36. Theoperation of the apparatus is identical to that disclosed in the saidpatent. For example, the position of wiper 61 may be manually adjustedto cause piston 19 to move downwardly as viewed in FIG. 1. In this case,orifice 36 will be closed off in proportion to the setting of wiper 61or all the way. As stated previously, a three-way valve is in a positionthat conduit 34 has free and open communication with orifice 36.Pressure will thus build up behind orifice 36 and conduit 34 and inchamber 28. The increase in pressure in chamber 28 will cause spring 29to compress. Diaphragm 30 will then lift and close off ball valve 24.The bleed through ball valve 24 being cut off, pump 11 will begin toincrease the pressure in device 14 above piston 19. The piston 19 willthen be driven downwardly. The feedback from rod 21 to wimr 28 willeventually rebalance the system to a particular setting 'of vave 39.Rebalance will occur at a setting of valve 39 corresponding to thesetting of wiper 61. A change in the position of wiper 61 will cause acorresponding change in a similar manner in the setting of valve 39.

If wiper 61 simply sets piston 19 further downwardly, the operation isidentical to that just described. It the setting of wiper 61 tends torelieve the pressure above piston 19, such relief is provided asfollows. Flapper valve 50 opens orifice 36 wider. The pressure then inconduit 34 and chamber 28 declines. Spring 29 then presses diaphragm 30downwardly, and valve 24 is opened wider. The bleed from pump 11 is thusincreased and the pressure above piston 19 reduced. The piston 19therefore will rise responsive to the pressure of spring 63.

The foregoing is a description of the operation of the apparatus shownin FIG. 1 when valve 37 connects conduit 34 with orifice 36. In thiscase, conduit 34 is not connected to valve P or orifice 35.

The second mode of operation of the invention is effected by closing 01fconduit 34 from orifice 36 by the use of valve 37, and by connectingconduit 34 to valve P and orifice 35. Let us assume this condition. Letus further assume that valve 39 is closed when piston 19 is in theposition shown in FIG. 1. If valve 37 connects conduit 34 to valve P andorifice 35 while piston 19 is in the position shown, nothing happens.The pressure above piston 19 is bled ofl? through orifice 35, but thepressure is already insufiicient to open valve 39. On the other hand, ifpiston 19 is spaced downwardly from the position shown in FIG. 1,bleeding the pressure above piston 19 off through orifice 35 will causevalve 39 to close slowly. This is true because the hydraulic fluid issubstantially incompressable. So long as pump 11 is operating, piston 19must be maintained stationary or moved downwardly unless sutficientfluid is bled 011 from the top of piston 19. However, if this fluid isbled off to fast, valve 39 will close rapidly. Fluid is bled olf inaccordance with the device of the present invention at orifice 35. Asbefore, this reduces the pressure in conduit 34 and chamber 28. Spring29 then moves diaphragm 30 downwardly and opens valve 24. Fluid is thusbled off from the top of piston 19 through conduit 17.

An identical system is shown in FIG. 2, except that system 38 andorifice 36 are omitted. Further, a solenoid valve 40 replaces solenoidvalve 37. In the operation of the embodiment of FIG. 2, solenoid valve40 simply closes off conduit 34 and closes valve 39. When solenoid valve40 opens, valve 39 slowly closes as the pressure inside amplifier 23 isbled off slowly through orifice 35.

In accordance with the foregoing, a large opening force and closingforce may be controlled by small solenoid valves 37 and 40. Moreover,valve 39 can be controlled to close slowly simply by the use of thebleed orifice 35.

An adjustable valve P is employed ahead of orifice 35 to adjust theeffectiveness of orifice 35.

What is claimed is:

1. A hydraulic system comprising: a fluid pressure responsive device;motive power means for supplying a hydraulic fluid under pressure tosaid device; a hydraulic amplifier having an input conduit from saidmotive power means and an output conduit; a fixed restricted orifice; amain valve connected between said output conduit and said orifice in aposition to allow fluid flow from said output conduit to flow throughsaid orifice, said main valve being movable to a position for increasingthe pressure of the fluid supplied from said amplifier to actuate thechamber connected between its input and output conduits, an auxiliaryvalve at the input conduit to throttle flow therefrom into said chamber,and means responsive to the pressure in said chamber to close saidauxiliary valve an incremental amount each time the pressure in saidchamber increases an incremental amount.

2. The invention as defined in claim 3, wherein said main valve is athree-way valve connected to an additional orifice, said motive powermeans including control means with a flapper valve to press against thefluid emanating from said additional orifice to control the position ofsaid pressure responsive device.

3. The invention as defined in claim 1, wherein a manually adjustablevalve is positioned between said main valve and said orifice.

References Cited UNITED STATES PATENTS PAUL E. MASLOUSKY, PrimaryExaminer US. Cl. X.R. 91363, 446, 461

